Microtelephone.



J. N. WALLACE.

MIOROTELEPHONE.

APPLICATION FILED MAR. 22, 1909.

Patented Aug. 16, 1910.

2 SHEETS-SHEET 1.

J. N. WALLACE.

MIGROTELEPHONE.

APPLIOATION FILED MAR. 22, 1909.

967,276, Patented Aug. 16, 1910.

2 SHEETS-SHEET 2.

UNITED STATES PATENT OFFICE.

JOHN N. WALLACE, OF LA CROSSE, WISCONSIN, ASSIGNOR T0 VOTE-BERGER COMPANY,

OF LA CBOSSE, WISCONSIN.

MICROTELEPHONE.

Specification of Letters Patent.

Patented Aug. 16, 1910.

Application filed March 22, 1909. Serial No. 484,870.

of which the following is a specification.

My invention pertalnsto microtelephones. Byfthis term is meant an integral device comprising a microphonic telephone transmitter and an electromagnetic telephone receiver.

My improvement in microtelephones consists of introducing an additional element of the telephone set into the integral structure of the microtelephone, thereby enabling my device to be a complete speeoh receiving and speech-transmitting set, conforming to the rigid requirements of modern common battery telephone practice.

It is the requirement in modern practice that a telephone receiver shall not be affected by direct current flowing over the telephone line. Many circuits have been suggested, and some of them have been adopted,

and have been used successfully, to effect this result. One of the most widely used of these circuits is that in which the transmitter and the primary winding of an induction coil are connected in series with each other, and in the line circuit, and the receiver is then connected to-the secondaryof the induction coil nzentioned. I have adapted this type of circui for illustration to the inte ral microtelephone of my invention by inc ud.- ing the induction coil within the microtelephone structure. I

One of the important advantages attained by my improved microtelephone is that it requires but two conductors in its flexible cord, while at the same time it attains the desirable feature ofthe circuit above outlined. 4

In the drawings, Figures 1 and 2 show two views of the complete microtelephone of my invention, taken in directions at right angles to each other. Fig. 3, which comprisesan entire sheet of drawings, shows all of the parts of the microtelephone, separated from each other, but arran ed in such relative positions that their assem 1 may be understood. In Fig. 3, the telephone receiver and the telephone transmitter have been omitted, since no features of invention to be claimed in this application are involved in those elements. Like numbers refer to similar parts throughout the several views.

The frame upon which all parts are as sembled comprises a splittubul'ar part, of which the part 1 may be considered a base part and the part 2 a cover part. Upon the part 1 are mounted induction coil 3 and switch t. Switch 4 comprises two contact springs, normally separated, one having a 5 push button 4', which when ressed closes the parts together electrica y. The line circuit of the device enters through conductor 5, thence through switch' i, through primary of coil-3 and conductor 6 to transmitter, thence returning over conductor 7. The secondary, having terminals at S, is connected tothe receiver. The cover. 2 now may be placed loosely upon the part 1, and the surface member, or finishing member 8, is slipped over the cylindrical structure formed by the parts 1 and 2, the button 4' projecting therethrough, and the set screw 9 holding the part 8 in position. End caps 10 and 11 close the ends of the cylindrical structure formed by parts land 2, and receiver 12 and transmitter 13 are attached by screws, whichpass throu h the end caps and into-the part 1. Taper Eushings 14 and 15 are interposed between the receiver and the end cap, and the transmitter and the end cap'respectively.' These bushings, by offering one curved face and one plane face, afford a' rigid mounting for the receiver and transmitter respectively, and b their tapered form control the an le which the face of the receiver and the ace of the transmitter makewith each other. It is found .by experiment that .when a short mouth .plece or funnel, suchas is shown at 13, is

used upon a microtelephone, that the mouth piece cannot be held in front of the mouth a and the receiver held closely upon the car by the average tele hone user when the parts are mounted parallial to the axis of the handie. For this reason, the an les attained by the taper bushings are foun desirable.

The end cap 10 has an open end'for exit of flexible conductors 5 and 7; the end cap ll'has a closed end.

dle, thereby permitting the flexi le .cord to The end cap 10 may v be placed upon either the receiver end or the transmitter end of the microtele hone hanmake exit from the upper or lower end, as

the user may desire; end cap 11, of course,

is placed on the other end of the receiver. 1

It is essential that the device 3, which is shown as an induction coil, sh'all'have the characteristics of passing between its terminals P all currents from the transmitter, and shall differentiate the currents, or the energy of the currents,to ,pass from its terminals S as great a part as possible of the varying currents or of the varying component of the currents, and a negligible quantity or none of the direct currents. T he device 3, therefore, may be any current separating means.

It is obvious that many modifications, either in electrical circuits or minor mechanical details, are possible in the device ec zave handle member being composed of two half tubular members and two binding members adapted to hold said half tubular handle members together; said receiver and transmitter being attached to one of said half tubular handle members.

3. A microtelephone comprisinga handle member, a receiver and a transmitter, said handle member being composed of two half tubular members and two binding members adapted to hold said half tubular handle members together, said receiver and transmitter being attached to one of said half tubular handle members with their diaphragms in different-and parallel planes.

4. In a microtelephone a handle composed of two separable members jointly forming a tubular structure; a tube surrounding and uniting said members; means for attaching a transmitter and receiver to one of said members and an induction coil contained within the tubular structure formed by said members.

Signed by me at La Crosse, county of La Crosse, and State of \Visconsin, in the presence of two witnesses.

JOHN N. \VALLACE.

Witnesses:

GUS. LUNDGREN, LonEN S. REES. 

